Preparing Embedded Software Pipelines for Regulatory Audits with Timing Evidence

Hook: stop scrambling for timing evidence during audits

If your team dreads the regulatory audit because timing evidence is scattered across tools, ad-hoc traces, and unverifiable spreadsheets, this guide is for you. Teams building real-time embedded software now face auditors demanding reproducible timing evidence—WCET numbers, traceability to requirements, and a clear chain-of-custody for every artifact. This article shows how to produce auditable evidence from timing analysis tools (notably RocqStat), integrate it into a repeatable compliance pipeline, and assemble compliance artifacts ready for safety certification reviews in 2026.

Why timing evidence matters now (2026 context)

In late 2025 and early 2026 regulators and certification authorities across automotive, aerospace and industrial domains tightened expectations around timing verification. The acquisition of RocqStat by Vector in January 2026 is emblematic: vendors are consolidating timing analysis into unified toolchains to simplify WCET proof for auditors and reduce toolchain fragmentation.

"Timing safety is becoming a critical ..." — Eric Barton, Vector (statement on RocqStat acquisition, Jan 2026)

The practical impact: auditors now expect not only a reported WCET value, but evidence that the WCET was produced with a qualified toolchain, that the analysis is traceable to requirements, and that results are reproducible from preserved inputs. If you can automate this, audits are shorter and certification risk drops.

What auditors want from timing evidence

• Reproducibility — exact inputs, tool versions, and commands to regenerate WCET and timing artifacts.
• Traceability — mapping from requirements to code, tests, traces, and final WCET values.
• Integrity — tamper-evidence for artifacts: cryptographic hashes, signatures, timestamping.
• Tool Qualification — evidence that the timing tool is qualified or that its limitations are understood and mitigated (ISO 26262 / DO-178C context).
• Context — hardware configuration, compiler flags, and environment (RTOS, core bindings, caches) used for analysis.

Compliance pipeline: high-level architecture

Build a compliance pipeline that converts timing analyses into audit-ready artifacts. Key stages:

1. Capture — collect traces, source code, requirements IDs, build metadata and hardware descriptions.
2. Analyze — run RocqStat (or another timing analyser) to produce WCET and statistical evidence.
3. Enrich — attach traceability metadata linking results to requirements and test cases.
4. Seal — compute hashes, sign results, and get RFC3161 timestamps to show when artifacts existed.
5. Archive — store artifacts in WORM-capable or write-once repositories with access logs for chain-of-custody.

Step-by-step: Producing auditable timing evidence with RocqStat

Below is a concrete, practical workflow your team can adopt. Replace the placeholders with your project specifics.

1) Lock the environment (reproducibility)

Capture exact toolchain and environment with a container image and a manifest. Use deterministic build tools (Nix, Bazel sandboxing) when possible.

# Example: Dockerfile snippet for reproducible analysis environment
FROM ubuntu:22.04

# Pin RocqStat version and other tools
ENV ROCQSTAT_VERSION=2.4.1
RUN apt-get update && apt-get install -y build-essential python3 git curl \
    && curl -L -o /usr/local/bin/rocqstat "https://example.com/rocqstat/$ROCQSTAT_VERSION/rocqstat"

# Freeze versions in a manifest file
RUN rocqstat --version > /env_manifest.txt && git --version >> /env_manifest.txt

Include the env_manifest.txt in your audit artifact so auditors can verify the exact runtime.

2) Instrument and collect traces

Use consistent instrumentation (tracepoints, hardware performance counters) and name trace files with requirement IDs and build SHA.

# Example trace filename convention
app-main_rq-REQ1234_build-_hwCORE0.trace

Collect hardware config: CPU model, frequency, cache details, RTOS version, and scheduler settings. Save as hardware.json.

3) Run RocqStat to generate WCET and statistical evidence

Run RocqStat in a deterministic way and capture its machine-readable outputs (JSON/XML) plus human-readable reports (PDF/HTML). Always save the exact command line.

# Example RocqStat invocation (pseudo-command)
rocqstat analyze \
  --trace app-main_rq-REQ1234_build-abc123.trace \
  --hw-config hardware.json \
  --output results/REQ1234_rocqstat.json \
  --report results/REQ1234_rocqstat.pdf \
  --seed 42

# Save the command used
echo "rocqstat analyze --trace ... --seed 42" > results/REQ1234_cmd.txt

Keep the JSON output as primary evidence: it is machine-verifiable and easier to link into compliance artifacts.

4) Produce traceability metadata

Create a small mapping file that ties the RocqStat results to requirements, source commits and tests. Example format below is intentionally simple and human-readable.

{
  "requirement_id": "REQ1234",
  "source_commit": "abc123",
  "binary": "app-main.bin",
  "trace_files": ["app-main_rq-REQ1234_build-abc123_hwCORE0.trace"],
  "analysis": {
    "tool": "RocqStat",
    "version": "2.4.1",
    "output": "results/REQ1234_rocqstat.json",
    "wcet_us": 2450.0
  }
}

5) Seal artifacts for integrity and timestamping

Compute SHA-256 hashes for every artifact, sign with a project key (preferably HSM-backed), and obtain an RFC3161 timestamp (TSA) for the signed bundle. Auditors expect tamper-evidence and an attestation of when artifacts existed.

# Compute hashes
sha256sum results/* > results/hashes.txt

# Sign the hash file (using an HSM-backed key)
openssl dgst -sha256 -sign /keys/project_signing_key.pem -out results/hashes.sig results/hashes.txt

# RFC3161 timestamp (example)
curl -s --data-binary @results/hashes.sig https://tsa.example.com/timestamp > results/hashes.sig.tst

6) Archive and make auditable

Archive the signed bundle and artifacts in a WORM or access-controlled object store. Include an index file that auditors can open as the entry point.

# Build the archive index (audit_index.json)
{
  "project": "BrakeController",
  "build": "abc123",
  "artifacts": [
    "results/REQ1234_rocqstat.json",
    "results/REQ1234_rocqstat.pdf",
    "results/hashes.txt",
    "results/hashes.sig",
    "results/hashes.sig.tst",
    "env_manifest.txt",
    "hardware.json",
    "trace_files/app-main_rq-REQ1234_build-abc123_hwCORE0.trace"
  ],
  "archive_location": "s3://company-archives/BrakeController/abc123/"
}

Record access logs and retention policy. Keep artifacts per project retention requirements and the certification authority’s rules.

CI/CD integration: automate artifact generation

Add a compliance stage to your CI to produce and seal timing artifacts when a release candidate is created. Below is a simplified GitHub Actions job that runs the above steps.

name: wcet-evidence
on:
  workflow_dispatch:

jobs:
  generate-evidence:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Build container
        run: docker build -t project-analysis:latest .
      - name: Run RocqStat analysis
        run: |
          docker run --rm -v ${{ github.workspace }}:/work project-analysis:latest \
            bash -c "rocqstat analyze --trace /work/traces/REQ1234.trace --hw-config /work/hardware.json --output /work/results/REQ1234_rocqstat.json"
      - name: Seal and upload
        run: |
          docker run --rm -v ${{ github.workspace }}:/work project-analysis:latest \
            bash -c "cd /work && sha256sum results/* > results/hashes.txt && openssl dgst -sha256 -sign /keys/project_signing_key.pem -out results/hashes.sig results/hashes.txt"
      - name: Upload Evidence
        uses: actions/upload-artifact@v4
        with:
          name: wcet-evidence-abc123
          path: results/**

The CI job preserves the exact steps and artifacts, creating a reproducible trace for auditors.

Traceability: linking WCET to requirements and tests

Traceability is more than a file reference — make it a first-class artifact. Use an automated mapping from test case IDs and requirement IDs to the analysis outputs. Two practical approaches:

• Embed requirement IDs in test names and trace metadata so trace files are discoverable by ID.
• Maintain a traceability database (YAML/JSON/SQL) that maps requirement -> source file, test case -> trace file, analysis output -> artifact path.

A single query should allow auditors to see: REQ1234 -> test TC-45 -> trace file -> RocqStat output -> sealed archive.

Tool qualification and limitations

Timing tools like RocqStat are powerful, but safety certification regimes often require tool qualification or a documented mitigation strategy. For example:

• ISO 26262 (Automotive) — tools affecting safety goals may need qualification evidence (TQL) or a defined tool confidence level.
• DO-178C (Aerospace) — tool qualification objectives must be met if the tool can inject errors not detected by other means.

Practical steps:

• Record the tool qualification status and include it in the archive. If a third-party (Vector/RocqStat) provides a qualification kit, save it alongside your artifacts.
• When the tool is not qualified, provide independent verification (e.g., cross-check with measurement-based methods, formal analysis, or redundant tooling) and a rationale why the approach is acceptable.
• Keep vendor communications (emails, acquisition notices) to show continuity of support and expected stability. The 2026 Vector acquisition of RocqStat is a relevant example showing vendor consolidation and longer-term support commitments.

What auditors will test during the review

Expect auditors to run a few checks and ask for reproduction. Common inquiries:

• Can you re-run the analysis from the archived inputs and produce the same numeric WCET?
• Is the tool version the same as recorded and is it on the allowed/qualified list?
• Are hardware and OS configurations identical or adequately modelled?
• Do traceability links prove that REQ1234 has WCET evidence covering all relevant code paths?
• Is there evidence of tamper resistance (signed artifacts and timestamps)?

Presenting evidence to auditors: a recommended artifact bundle

Make it easy for auditors: provide a single zipped (or WORM) bundle with an index. Minimal recommended contents:

1. audit_index.json — entry point describing contents and steps to reproduce.
2. env_manifest.txt — tool versions and container digest.
3. hardware.json — hardware and OS configuration.
4. trace files — named with requirement/test IDs.
5. rocqstat JSON outputs + human-readable PDFs.
6. traceability.json — requirement -> trace -> analysis mapping.
7. hashes.txt, hashes.sig, hashes.sig.tst — integrity and timestamping artifacts.
8. tool_qualification.pdf — vendor qualification kit or mitigation description.
9. repro_instructions.md — exact commands to reproduce results.

Advanced strategies and future-proofing (2026+)

As integrated toolchains like VectorCAST+RocqStat emerge, expect more automated evidence generation and vendor-supplied qualification kits. Consider these advanced tactics:

• Hardware-in-the-loop (HIL) proof artifacts: capture HIL logs and tie to timing evidence for systems that cannot be fully analysed on desktop hardware.
• Deterministic CI artifacts: use immutability (container digests) and signed manifests so artifacts remain reproducible long-term.
• Hybrid static + measurement evidence: combine static worst-case analysis (RocqStat) with targeted measurement campaigns for confidence in WCET assumptions—document the reconciliation strategy.
• Automated tool qualification tracking: store tool qualification status and associated evidence in the compliance repository to avoid last-minute surprises during audits.

Case study (short): integrating RocqStat into a certification run

A mid-size automotive software team used RocqStat to analyze brake control tasks across three ASIL-B components. They automated trace capture in nightly CI, ran RocqStat with pinned versions, and produced signed JSON outputs linked to JIRA requirement IDs. During an ISO 26262 audit in 2025, the auditors reproduced three WCET runs in under an hour using the provided container, and acceptance was achieved after the team supplied the vendor's qualification kit. The key success factors were reproducibility, signed artifacts, and clear traceability.

Quick checklist: audit-ready timing evidence

• Environment locked (container digest + env_manifest)
• All trace files named with requirement/test IDs
• RocqStat JSON + PDF outputs preserved
• Traceability mapping file linking requirements -> traces -> analysis
• Hashes, digital signatures, and RFC3161 timestamp
• Tool qualification status or mitigation documented
• Archive accessible with access logs and retention policy

Closing guidance: keep the audit short, tame the timing risk

In 2026, audit expectations have shifted from “show a WCET” to “show reproducible, traceable, and signed evidence of timing analysis.” Adopt a pipeline that treats timing evidence as a first-class artifact: lock environments, automate runs with RocqStat, attach traceability, and seal artifacts cryptographically. Doing so reduces friction during regulatory audits and materially lowers certification risk.

Call to action

Ready to implement an auditable timing evidence pipeline? Start by: 1) pinning your RocqStat toolchain in a container, 2) adding a single CI job that produces JSON outputs and hashes, and 3) creating an audit_index.json for one critical requirement. If you want a checklist template or a sample GitHub Actions workflow tailored to your repo, request the template and we’ll send a ready-to-run package that integrates RocqStat outputs into an ISO 26262/DO-178C-friendly artifact bundle.

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